Sydney, Melbourne drenched with rain as large hail forecast for NSW

Sydney and Melbourne are set to be soaked during a wet outbreak sweeping the south-east Australia coastline, with large hail already battering parts of New South Wales.

The Bureau of Meteorology has issued an immediate severe weather warning for 12 areas across NSW, with reports of hailstones as wide as five centimetres falling in some areas, most notably the Blue Mountains bearing the brunt of an intense storm.

"Severe thunderstorms are likely to produce large hailstones and damaging winds in the warning area over the next several hours," the warning read.

"Locations which may be affected include Armidale, Orange, Canberra, Goulburn, Tamworth, Gunnedah, Walgett, Dubbo, Parkes, Wagga Wagga, Albury and Lightning Ridge,"

Of those areas, Canberra has been subject to one of the worst batterings, with torrential storms sweeping the Australian Capital Territory, with no sign of the weather easing as it heads into Friday evening.

Residents in impacted areas are advised to stay indoors, secure all outside items and not to use the phone during storms.

Sydney is set for a soaking with up to 20mm of rain on Friday evening, with storms and blustery winds predicted.

Saturday doesn't fare much better with rain expected, with around 10mm of rain to fall across the course of the day.

And the wet weekend looks set to kick off a period of seven days of rain across the state.

Victoria will also face heavy rainfall that may lead to flash flooding as well as hail over the course of Friday evening.

Locations which may be affected include Wodonga, Traralgon, Sale, Moe, Bairnsdale and Orbost.

Strong winds are also predicted along the East Gippsland coastline.

Melbourne won't escape the downpour with heavy rain expected Friday evening while potential thunderstorms could hit on Saturday.

Unfortunately for Queensland, the state will not escape the bad weather with Brisbane set to cop a share of the rainfall with up to 15mm expected over the weekend.

However there is good news for South Australia, who will avoid the wet front and dry conditions are expected for Adelaide in the coming days.